U.S. Secretary of State John Kerry and U.S. Defense Secretary Chuck Hagel travel to Beijing this week for meetings with their Chinese counterparts on trade and security issues. Those talks are expected to include discussions on new Chinese oil rigs in disputed waters off Vietnam that are driving up tensions in the South China Sea.

Vietnam says the oil rigs are within its territorial waters and released a video of what it says is a Chinese vessel ramming a Vietnamese fishery control boat near the site.

Vietnam is working with the Philippines on legal challenges to Chinese claims in the South China Sea -- where Malaysia, Brunei, and Taiwan also have competing claims. Vietnam is especially vulnerable, according to American University professor Hillary Mann Leverett.

"Both Japan and the Philippines have a defense treaty with the United States where the United States is obligated to come to their defense even over a craggy island. We don't have that with Vietnam. So China can push Vietnam even further than it pushes Japan or the Philippines," she said.

Naval engagements

Chinese Foreign Ministry spokesman Qin Gang said those pushing for international arbitration in the South China Sea are violating legal norms.

"Some countries are waving the signboard of 'law' to encroach upon the legitimate rights and interests of other countries, putting on a 'legitimate' cloak to cover up their law-violating behaviors," said Qin.

While the United States is helping upgrade the Filipino navy, Washington is not taking a position on any of the rival claims in the South China Sea.

American Enterprise Institute analyst Michael Auslin said, "But that doesn't mean that our policy should be frozen or paralyzed when we see China acting coercively or acting aggressively. There's lot of things we can do. But the Obama administration, at least in this term, has decided that it is going to use the fig leaf of legal ambiguity in order not to get involved."

Auslin said this undercuts the value of this week's Strategic and Economic Dialogue, or S&ED. "Seriously, we have to ask what is the point of the S&ED anymore? It has achieved nothing substantive."

The Foreign and Defense Ministers' talks in Beijing follow China's navy joining, for the first time, U.S.-led naval exercises off Hawaii. U.S. officials say that could help address multilateral challenges. Chinese officials say it shows what it calls "the positive attitudes of the Chinese armed forces in maintaining regional security and stability.